JPH03220792A - Mounting structure of pga-type integrated circuit - Google Patents

Abstract

PURPOSE:To enhance the quality and the reliability of a solder connecting part by providing a recess part into which the tip part of a lead is inserted in a printed board, and providing conductive films for soldering around the opening edge of the recess part at the surface of the printed board. CONSTITUTION:In a circuit board 2 for mounting a butt-lead PGA-type LSI (PGA) package 1, a dent 3 as a recess part is formed at a part corresponding to the butt lead 1b of the PGA package 1. Conductive films 6 and 7 for soldering are provided around the opening edge of the recess part 3 at the surface of the printed board 4. At this time, soldering is performed under the state wherein the tip part of the lead is inserted into the recess part. Thus, the deviation of the lead in the lateral direction in soldering can be prevented.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a mounting structure for a PGA type integrated circuit in which a large number of leads erected on the bottom surface of a package of the PGA type integrated circuit are soldered to a printed circuit board. .

[Conventional technology]

Conventionally, PGA type integrated circuits have been manufactured using bathotory FPGAs, which have many butt leads erected on the bottom surface of the package body.
There is a type LSI package (hereinafter referred to as a PGA package for cars). In order to mount this PGA package on a printed circuit board, soldering of a conductive material provided on the surface of the printed circuit board is carried out by soldering a butt lead to the part. The soldering method used is so-called reflow soldering, in which solder paste is applied to the part of the printed circuit board, and the solder paste is heated while being positioned to support the butt lead. was.

[Problem to be solved by the invention]

However, in the conventional mounting structure in which the PGA package is soldered onto the printed circuit board, the printed circuit board is soldered on a flat part, and the soldering is sometimes carried out by heating with the hatch lead supported on this flat part. Therefore, during soldering, the butt lead tends to shift laterally with respect to the soldering part, causing misalignment. If the butt lead is misaligned, electrical continuity may occur or the quality and reliability of the solder joint may be compromised. In order to eliminate such problems, it is best to check for misalignment when soldering, but due to the small dimensions of the bunt leads and the large number of leads, soldering of PGA packages should be done in parts. It was very difficult to confirm visually.

[Means to solve the problem]

In the mounting structure of a PGA type integrated circuit according to the present invention, a recess is provided in the printed circuit board into which the tip of the lead is inserted, and a conductive coating for soldering is provided around the opening edge of the recess on the surface of the printed circuit board. It was established.

[For production]

Since soldering is performed with the tip of the lead inserted into the recess, soldering can sometimes prevent the lead from shifting laterally.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to FIGS. 1 and 2.

FIG. 1 is a perspective view showing a PGA type integrated circuit used in the PGA type integrated circuit mounting structure according to the present invention, and FIG. 2 is a sectional view showing the PGA type integrated circuit mounting structure according to the present invention. In these figures, 1 is a hatch-lead PGA type LSI package (hereinafter simply P) as a PGA type integrated circuit.
It's called GA package. ) is shown. This PGA package 1 is composed of a package body 1a which contains a semiconductor element (not shown) and is made of ceramic or the like, and a number of hatch leads 1b which are erected on the lower surface of the package body 1a. The dimensions of this bat lead 1b are approximately 0.2n in diameter and approximately 2R in length, and the pitch of a large number of hunt leads 1b is 1.27u.

Reference numeral 2 denotes a circuit board on which the PGA package 1 is mounted, and the circuit board 2 has a recess 3 formed in a portion corresponding to the butt lead 1b of the PGA package 1. Moreover, this circuit board 2 has upper and lower boards 4.5
The upper substrate 4 is formed with a through hole for forming the recess 3. That is, in this circuit board 2, the recess 3 is formed by overlapping the upper and lower boards 4.5 and closing the lower opening of the through hole with the lower board 5. In addition,
In order to form the recess 3, in addition to dividing the circuit board 2 into upper and lower halves as described above, it can also be formed by machining or the like on a single circuit board.

6 and 7 are conductive members connected to the bat lead 1b by solder 8, the surfaces of these conductive members 6 and 7 are coated with a conductive material, and the conductive member 6 is located at the bottom of the recess 3. The conductive member 7 is provided around the opening edge of the recess 3 on the surface of the circuit board 2 .

Next, the circuit board 2 provided with the recess 3 in this way is
The procedure for implementing A package 1 will be explained. First, solder paste (not shown) is applied to the recess 3 of the circuit board 2 so as to cover the conductive member 6.7. Then,
The butt lead 1b is inserted into this depression 3. By performing reflow soldering in this state, the PGA package 1 can be mounted on the circuit board 2. After the opening, as shown in FIG. 2, the space between the butt lead 1b and the inner wall of the recess 3 is filled with solder 8, and the conductive members 6 and 7 are connected to the hat lead 1b via the solder 8. It turns out.

Therefore, according to the present invention, since soldering is performed with the tip of the butt lead 1b inserted into the recess 3, it is possible to prevent the bunt lead 1b from shifting laterally during soldering.

Furthermore, in this embodiment, since the conductive member 6 is provided at the bottom of the recess 3, it is possible to easily melt the solder 8 into the recess 3, which has a relatively small diameter, so that soldering can be performed more reliably. .

[Effects of the Invention] As explained above, the mounting structure of the PGA type integrated circuit according to the present invention is such that the printed circuit board is provided with a recess into which the tip of the lead is inserted, and the opening edges of the four portions on the surface of the printed circuit board are formed. Because a conductive coating is provided around the area for soldering,
Since soldering is performed with the tip of the lead inserted into the recess, the lead can be soldered while being held in position. Therefore, soldering can sometimes prevent the leads from shifting laterally, thereby increasing the quality and reliability of the solder joint. Also,
Since the inside of the recess is filled with solder, the amount of solder can be increased, so the strength of the solder joint, which was considered unstable in the conventional mounting structure, can be improved. For this reason,
It is possible to maintain the solder joints with high reliability over a long period of time, and there is also the effect that inspection of the solder joints can be eliminated.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a PGA integrated circuit used in a PGA integrated circuit structure according to the present invention, and FIG. 2 shows a PGA integrated integrated circuit structure according to the present invention. FIG. DESCRIPTION OF SYMBOLS 1... PGA package, 1a... Package body, 1b... Hat lead, 2... Circuit board, 3... Recess, 6, 7... Conductive member, 8・・・
··solder.

Claims (1)

[Claims] In a mounting structure for a PGA type integrated circuit in which a large number of leads erected on the bottom surface of a PGA type integrated circuit package are soldered to a printed circuit board, a recess into which the tips of the leads are inserted is provided in the printed circuit board, and a recess is provided in the printed circuit board. A mounting structure for a PGA type integrated circuit, characterized in that a conductive coating for soldering is provided around the opening edge of the recess on the surface.